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United States Patent Office.


Specification forming part of Letters Patent No. 646, dated March 
21, 1838.

To all whom it may concern:

Be it known that we, Joseph Baughman, of Herford township, in the 
county of Berks, and. Julius Guiteau, of Mauch Chunk, in the 
county of Northampton, in the State of Pennsylvania, have 
invented a new and Improved Mode of Constructing Furnaces for and 
of Smelting Iron Ore by Means of Anthracite Coal as Fuel; and we 
do hereby declare that the following is a full, clear, and exact 
description thereof.

The dimensions of the respective parts of our furnace which we 
are about to give are such as will designate one of moderate 
size, our object being to afford a clear view of the general 
construction and arrangement thereof without intending thereby to 
limit Ourselves to the precise admeasurement set down. They will, 
however, exhibit a general character by which any competent 
ironmaster will be enabled to see the difference between our 
furnace and all those which have preceded it, and also to 
construct the same. The whole height of a furnace which we have 
essayed and found to answer well is twenty-four feet and four 
inches, the height above the hearth being twenty feet, leaving, 
of course, four feet four inches for the whole height of the 

In the accompanying drawings, Figure 1, (which is a vertical 
section of the furnace,) A is the hearth, measuring from the 
bottom to the top at B fifty-two inches, of which the measurement 
from the bottom to C is forty inches, and from C to B one foot. 
The hearth at bottom is sixteen inches wide and fifty-two inches 
long. The part C is eighteen inches diameter, and B fourteen 
inches, this being the upper part of the hearth and bottom of the 
boshes. The part extending from C to B is round at B, where it 
joins the boshes; but at C, where it measures eighteen inches and 
joins the hearth proper, it is worked off to a square 
corresponding to the shape of the hearth. The height of the 
boshes from B to D is six feet, the diameter at D being four feet 
six inches, giving to the boshes an inclination from the 
perpendicular of three inches and a half to the foot. The slope 
of this part is a point of considerable importance, as it in a 
great degree regulates the pressure of the charge, and adapts the 
furnace to the particular kind of fuel employed. The body of the 
furnace from D to D1 is twenty feet, and its diameter at D' two 
feet. E E represent the tuyeres for the blast, one, two, or three 
of which may be used. In our experiments we have found but one 
necessary, which we have found to answer perfectly well with a 
cold blast, (although the hot blast was tried,) at a pressure of 
two and one-half pounds to the inch. A water-tuyere is in all 
cases to be preferred. The general construction and arrangement 
of the furnace thus far, it will be seen, do not present anything 
peculiar. Our manner of constructing and arranging the dam-stone, 
however, we deem to be new, without which, or some means whereby 
fluid iron is constantly kept on the hearth, a furnace cannot be 
kept in continuous action with anthracite coal as a fuel.

Fig. 2 shows the front of the hearth, exhibiting the dam-stone 
and false dam-stone as arranged and used by us. This front is 
forty inches in height and eighteen inches wide at the top and 
sixteen at the bottom. The dam-stone F is twelve inches long and 
twelve inches high, and it is about the same in depth from front 
to inside. G is what we denominate the "false-dam-stone." This is 
four inches in width and four in height, filling up the space in 
the width not occupied by the dam-stone. This of course is raised 
to the height of the dam-stone in the usual manner by clay and 
sand, into which the tapping-holes are to be made. The blast is 
to be introduced at the height of sixteen inches from the bottom 
of the hearth, and four inches, of course, above the dam-stone. 
In the blast-pipes H H are funnels placed about three feet from 
their small ends, which funnels may, in case of the deadening of 
the fire at any time in the cold blast, be charged with charcoal 
or other fuel, which will be blown in and obviate this 
difficulty, as is known to the managers of furnaces.

In working our furnace it is requisite always to retain a 
quantity of fluid metal in the lower part of the hearth�say to a 
height from four to six inches�which is effected by means of the 
false dam-stone and the management of the tapping-hole. When it 
is desired to remove the metal below the top of the false 
dam-stone it may be dipped out as in the usual way.

To enable us to remove most of the fluid iron and still keep the 
scoria floating upon the metal, we sometimes throw in several 
pounds of lead, which melts and sinks below the iron, which it 
keeps from contact with the bottom of the hearth, while it is 
itself protected from the action of the atmosphere by the iron 
above it.

We first charge our furnace with charcoal, preparing and managing 
the ore, the flux, and the fuel in carrying on the process in the 
ordinary manner, not requiring to be particularly described, as 
varying with the nature of the materials, as things well known to 
every ' ironmaster. Another peculiarity in our furnace is the 
location and use of the flue or throat extending from the top of 
the hearth C to the bottom of the boshes B, as described, we 
having found this part of essential service in regulating the 
heat, the descent of the load, and consequently the quality of 
the iron.

What we claim as our invention, and wish to secure by Letters 
Patent, is�

1. The manner in which we arrange and employ the dam-stone and 
false dam-stone, substantially as by us set forth.

2. The inverted conical flue or throat, as described, between the 
top of the hearth proper and the boshes.

3. The employment of lead, in the manner and for the purposes 
herein shown.

We wish it to be further understood that we intend to use a 
furnace of the kind described�that is to say, one with the 
dam-stone, the false dam-stone, and the flue or throat�for the 
purpose of smelting iron with coke of bituminous coal, employing 
also the same precautions in the use of lead and in all other 
points as we employ when anthracite is the fuel, so far as the 
same may be found necessary or useful in their application.


Witnesses: Jacob H. Boyer, Henry Geoff.